1. Field of the Invention
The invention relates to a method for determining the real power of an electrical drive, preferably an electrical fitting drive, which includes subtracting an ohmic or resistive power loss produced in a stator of the drive from a measured real power. The invention also relates to a device for determining the real power of an electrical drive, preferably an electrical fitting drive, which includes connecting lines for stator windings of the drive.
A fitting diagnosis is a measurement and evaluation method which can be carried out on a fitting. The use of that method permits early identification of whether or not the condition of the fitting has changed in such a way that there is a risk of failure or at least restricted operation of the fitting. Fitting diagnosis includes measurement of the real power of an electrical drive of the fitting. Any change in the real power, particularly in conjunction with a change in other variables, indicates a defect in the fitting.
It is already known for the measured real power to have to be corrected before it can provide information on the condition of the fitting.
It has already been proposed for the ohmic or resistive loss in the stator of the fitting drive as well as the inductive loss in the stator and the ohmic or resistive and inductive losses in the rotor of the drive to be subtracted from the measured real power in order to correct the real power.
The corrected real power values which are obtained in that way are subject to fluctuations which cannot be traced back to defects in the fitting. Reliable fitting diagnosis is thus impossible by using those corrected values of the real power of an electrical drive.